Assessment of the Phytotoxicity of Metal Oxide Nanoparticles on Two Crop Plants, Maize (Zea mays L.) and Rice (Oryza sativa L.)

Abstract

In this study, the phytotoxicity of seven metal oxide nanoparticles(NPs)—titanium dioxide (nTiO2), silicon dioxide (nSiO2), cerium dioxide (nCeO2), magnetite (nFe3O4), aluminum oxide (nAl2O3), zinc oxide (nZnO) and copper oxide (nCuO)—was assessed on two agriculturally significant crop plants (maize and rice). The results showed that seed germination was not affected by any of the seven metal oxide NPs. However, at the concentration of 2000 mg·L−1, the root elongation was significantly inhibited by nCuO (95.73% for maize and 97.28% for rice), nZnO (50.45% for maize and 66.75% for rice). On the contrary, minor phytotoxicity of nAl2O3 was only observed in maize, and no obvious toxic effects were found in the other four metal oxide NPs. By further study we found that the phytotoxic effects of nZnO, nAl2O3 and nCuO (25 to 2000 mg·L−1) were concentration dependent, and were not caused by the corresponding Cu2+, Zn2+ and Al3+ ions (0.11 mg·L−1, 1.27 mg·L−1 and 0.74 mg·L−1, respectively). Furthermore, ZnO NPs (<50 nm) showed greater toxicity than ZnO microparticles(MPs)(<5 μm) to root elongation of both maize and rice. Overall, this study provided valuable information for the application of engineered NPs in agriculture and the assessment of the potential environmental risks.

Influence of nano‐zinc oxide on tropane alkaloid production, h6h gene transcription and antioxidant enzyme activity in Hyoscyamus reticulatus L. hairy roots

“…A negative effect on growth was also observed after aluminum oxide nanoparticle treatment, which inhibited the root length of corn, cucumber, soybean, cabbage, and carrot [28]. Inhibition of root growth varies greatly among plants and according to the type and concentration of nanoparticles applied [29]. The negative impact of the ZnO treatment could be the result of a reduced permeability of the root cell membrane, since heavy metals interact with the sulfide groups in vacuoles, preventing water from penetrating the plant tissues [30].…”

Impact of iron and manganese nano-metal-oxides on contaminant interaction and fortification potential in agricultural systems – a review

“…Ferrihydrite and hematite nanoparticles with concentrations from 1 to 6 ppm, also in hydroponic systems, showed no visual signs of stress, but did increase seed germination, chlorophyll content and root growth compared with controls (Pariona et al 2017). In contrast to that study, Yang et al found that Fe 3 O 4 (magnetite) nanoparticles did not affect maize or rice (Oryza sativa) seed germination and root elongation at an application rate of 100 ppm (Yang et al 2015b). Another hydroponic study in rice investigated the effect of Fe-NMOs compared with FeSO 4 fertiliser and found that 100-ppm Fe-NMOs increased root length, shoot length, and dry and fresh weights compared with the FeSO 4 treatment, but at 200 ppm, no effect compared with FeSO 4 was observed, and a negative effect was observed at 400-ppm Fe-NMOs (Mankad et al 2017).…”

Engineered ZnO and CuO Nanoparticles Ameliorate Morphological and Biochemical Response in Tissue Culture Regenerants of Candyleaf (Stevia rebaudiana)

“…Similarly, Zafar et al [14] also endorsed the toxicological phenomena at 1000 mg/L in black mustard (Brassica nigra). Furthermore, the studies of Yang et al [6] on crop plants, corn (Zea mays) and Asian rice (Oryza sativa), reveal CuO ENPs to be more phytotoxic than ZnO ENPs. However, our study concluded ZnO ENPs to be more The maximum amount of phytotoxicity was obtained at 2000 mg/L in the current study by which physiological parameters, SGs, and non-enzymatic antioxidant activities mitigate to a minimum.…”